UPS contribution to system

[swiminelectricity]

I am doing a short circuit and load flow study for a system. When I ran the ETAP software, I notoced UPS sytem can cause the voltage rise and it does little contribution to the system short circuit. is it right?

 

[RonShap]

Does ETAP model a UPS?
I use SKM and it doesn't model a UPS, which is ok, because I get worst case results considering the bypass path.
A UPS output is limited during a fault to about 300%, so it transfers to bypass to help clear the downstream OCPD.

 

[dpc]

As mentioned, the response of a UPS to short circuit conditions depends on the UPS design and implementation. Without some type of automatic bypass, the SC response is very limited. The 300% figure mentioned above seems maybe optimistic.

With a bypass, the SC response is basically the same as if the UPS was not there and the system was fed via the mains.

 

[RRaghunath]

The UPS cannot contribute to the system fault, other than the one in the system downstream of the UPS. This too is in a very limited way, as already explained by dpc above.

raghunath_n00@rediffmail.com